Depending on their operating principles, there exist two kinds of touch panels, i.e., resistive touch panels and capacitive touch panels, and currently the latter has been widely used in electronic products. The capacitive touch panel, which operates by means of an induced current of a human body, may sense a touch signal through the combination of the characteristics of human body and electrodes. When the panel is touched by the human body (e.g., a finger), a coupling capacitance is generated between the finger and a conductive layer of the touch panel due to the existing of an electric field of the human body, and the current generated by the electrode on the touch panel will flow toward a contact point, so it is able to calculate a position of the touch point accurately.
Usually, a conductive film of the touch panel, as a part of great importance, includes a conductive layer and an insulating base material. The conductive layer is usually made of indium tin oxide (ITO) and formed on the insulating base material through vacuum-evaporation, patterning and etching. Then, the conductive film is adhered onto a transparent glass panel by an adhesive layer, so as to form the touch panel.
However, indium is scarce and expensive, so ITO is very expensive. In addition, when ITO is applied onto a surface of the entire insulating base material and then patterned and etched, a great quantity of ITO will be wasted, so the production cost of the conductive layer will increase remarkably.
In order to overcome these defects, a new-generation touch technique called “metal mesh” has been presented, where a metal mesh made of silver, instead of ITO, is arranged on the base material so as to form the conductive layer. However, the existing metal-mesh-type touch panel is of a single structure and non-compatible with a capacitance of a market-available touch driver chip, so the application of this kind of touch panel is limited.